Moody's decision to change its rating outlook for Germany from stable to negative is a warning shot. Although it is unlikely that Moody's decision will have any significant repercussions for the German government's refinancing costs, it should make German policymakers pause for thought. While the country has weathered the eurozone crisis rather well until now, its economy is likely to be dragged into the crisis sooner rather than later.

Until now Germany has mainly profited from the crisis. As a safe haven for eurozone investors who flee the crisis countries' bond markets, its interest rates are at an all-time low – and Moody's decision hardly made a difference to German bond yields. Moreover, last week the auction of German short-term bonds even led to negative yields. In other words, investors are so eager to invest in German bonds that they are even ready to pay for it. The private sector, whose interest rates depend on the government's, also faces historically low refinancing rates which stimulates investment and domestic demand. Also, since many investors turn their back on the eurozone altogether, the euro exchange rate has depreciated, thereby giving a boost to German exports outside of the eurozone.

So why is Moody's sceptical? The main reason is that the risks from within the eurozone have steadily accumulated and are likely to threaten Germany's economy. This is due to the high entanglements of German banks and its industry with the economies of today's crisis countries. Before the start of the crisis, German banks provided ample credit to those countries, especially to its private sector. In turn, the crisis countries used this money to import German goods. This gave a strong stimulus to the Germany economy which was in a protracted economic crisis in the first part of the 2000s.

While domestic demand stagnated, both German banks and German industry were happy to lend and sell abroad. Corporate profits rose to record levels. But when the boom came to a bust, those same banks were left with risky claims and strongly curtailed their lending to the crisis countries. With the dry-up of German lending, its industry in turn will have a harder time selling its goods abroad. About 40% of Germany's exports go to other eurozone members. Exports to Spain, Italy, Portugal and Greece have already dramatically fallen and the declining economic outlook for the rest of the eurozone threatens Germany's export industry.

But instead of helping its trade partners to both service their debts and maintain their imports, Germany's crisis policies have put both its banks and its industry at serious risk. Angela Merkel and her finance minister Wolfgang Schäuble have insisted on simultaneous cuts in public expenditures, cuts that deepen the economic crisis in those countries and thus limit their ability to import German goods and service German debts.

What's particularly strange about the current situation is that Germany faced a nigh-similar situation in 2008. Then, the bursting of the US housing bubble caused a global economic crisis; the dramatic fall in exports led to the deepest fall in German GDP since 1945. Many German banks had to be saved due to their bad investments in US structured mortgage instruments. Already then, banks' bad investments threatened financial stability. Saving the banks, as well as a big fiscal stimulus, increased the German government's debt ratio significantly.

In contrast to 2008 however, current German policy is not a helpless victim of globalisation's risks. It directly influences the future of the eurozone and its members. There are plenty of things Germany could do: help crisis countries by advocating less dramatic cuts in public expenditures; stimulate German growth in order to increase its imports from other eurozone members and help bring in the European Central Bank as a lender of last resort.

Unfortunately, this is very unlikely to happen. The economic consensus in Germany is that crisis countries overinvested in the past, and that they now have to suffer for their past sins. Moody's warning is unlikely to be heard. The German economy will pay the price.